Aerosol researchers are calling for more measures to be taken against the virus indoors

 "Leading aerosol researchers from Germany are calling for politicians to change course in the measures to contain the corona epidemic. "If we want to get the pandemic under control, we have to make people aware that the danger is lurking indoors," said a letter to the federal government and the state governments, which is available to the German Press Agency. It is considered certain that the coronavirus spreads mainly through the air. 

The authors recommend measures such as:

keeping indoor meetings as short as possible, 

frequent intermittent or cross ventilation, 

wearing effective masks indoors, 

as well as room air purifiers and filters wherever people have to stay longer in closed rooms - e.g. in nursing homes, offices and schools. 

"Unfortunately, to this day, the essential findings of our research work have not been translated into practical action," the authors criticize. Action would have to be taken in homes, offices, classrooms, residential complexes and care facilities. 

They warn that infection occurs indoors even if you do not meet someone directly, but an infectious person has been in a poorly ventilated room beforehand. 

Debates about strolling on river promenades, staying in beer gardens, jogging or cycling, however, are counterproductive. Measures such as compulsory masks when jogging along the Alster and Elbe in Hamburg are more of a symbolic nature and "do not have any significant impact on the infection rate," the experts write. 

Sars-CoV-2 viruses would almost always be transmitted indoors. 

This is extremely rare in the open air. The letter says that the limited resources should not be wasted on open air activities. 

Also, large groups - so-called clusters - are never infected outdoors, as can be observed indoors, for example in homes, schools, events, choir rehearsals or bus trips. 

From the point of view of the scientists, the curfews also promise more than they can deliver. "This does not prevent secret meetings indoors, but only increases the motivation to evade government orders even more," they write. "Wearing a mask in the pedestrian zone and then having a coffee table without a mask in your own living room is not what we, as experts, understand by preventing infection." With movement restrictions, politicians want to prevent people from meeting at all."